etcdserver: exit on missing backend only if semver is >= 3.0.0
etcdserver: exit on missing backend only if semver is >= 3.0.0

xiang90/etcd,mkumatag/etcd,YuleiXiao/etcd,vimalk78/etcd,gyuho/etcd,a-robinson/etcd,jonboulle/etcd,sinsharat/etcd,joshix/etcd,lumjjb/etcd,plasticbox/etcd,StorReduce/etcd,jonboulle/etcd,armstrongli/etcd,yudai/etcd,OyTao/etcd_learning,rchicoli/etcd,vimalk78/etcd,ravigadde/etcd,a-robinson/etcd,whuwxl/etcd,wantonsolutions/dinv-etcd,rnaveiras/etcd,sebrandon1/etcd,mqliang/etcd,joshix/etcd,plasticbox/etcd,mickep76/etcd,purpleidea/etcd,linuxcer/etcd,wantonsolutions/dinv-etcd,ajityagaty/etcd,tguangch/etcd,glevand/coreos--etcd,westhood/etcd,bluebreezecf/etcd,endocode/etcd,cockroachdb/etcd,CrazyJvm/etcd,swingbach/etcd,insequent/etcd,mickep76/etcd,fanminshi/etcd,ktateish/etcd,ajityagaty/etcd,armstrongli/etcd,handsomesun/etcd,bluebreezecf/etcd,YuleiXiao/etcd,heyitsanthony/etcd,glycerine/etcd,whuwxl/etcd,dannysauer/etcd,zaphod-concur/etcd,handsomesun/etcd,tguangch/etcd,mqliang/etcd,qqsun8819/etcd,li-ang/etcd,insequent/etcd,endocode/etcd,qqsun8819/etcd,gyuho/etcd,CrazyJvm/etcd,akauppi/etcd,linuxcer/etcd,cockroachdb/etcd,coreos/etcd,hongchaodeng/etcd,coreos/etcd,rnaveiras/etcd,fanminshi/etcd,etcd-io/etcd,xiang90/etcd,bdarnell/etcd,hongchaodeng/etcd,etcd-io/etcd,mkumatag/etcd,ravigadde/etcd,dannysauer/etcd,nekto0n/etcd,nekto0n/etcd,rnaveiras/etcd,glevand/coreos--etcd,etcd-io/etcd,wantonsolutions/dinv-etcd,lumjjb/etcd,ktateish/etcd,visheshnp/etcd,glycerine/etcd,jlamillan/etcd,sebrandon1/etcd,yudai/etcd,sinsharat/etcd,jlamillan/etcd,purpleidea/etcd,swingbach/etcd,westhood/etcd,mqliang/etcd,heyitsanthony/etcd,OyTao/etcd_learning,ajityagaty/etcd,akauppi/etcd,mkumatag/etcd,luxas/etcd,StorReduce/etcd,visheshnp/etcd,lorneli/etcd,lorneli/etcd,zaphod-concur/etcd,li-ang/etcd,bdarnell/etcd,luxas/etcd,rchicoli/etcd